This is WEEKEND EDITION from NPR News. I'm Scott Simon. When Stephen Carter's new novel opens, President Kennedy is alone in a bedroom with the beautiful intern. Did I say this was a novel? We'll let Professor Carter pick up his narrative.

STEPHEN CARTER: (Reading) Kennedy groaned. It occurred to Margo that in the midst of a crisis that could lead to nuclear war, the president had advisers galore but nobody to whom he could simply vent without backtalk. And so given that the plan required him to see Margo daily in any case, he had chosen her as his foil. It wasn't as though she could tell anybody. She could still not quite grasp that any of this was happening. It was October 1962, and a month ago she had been nobody. Now she was skulking around Washington, D.C., worried about being caught by someone who knew her or worse - by the people who would very much like her dead.

SIMON: Stephen Carter joins us from Yale University where he's the William Nelson Cromwell Professor of Law and a busy author of both nonfiction and best-selling fiction. His new novel is "Back Channel," and it tells a story that involves the Kennedy brothers, Bobby Fischer, late-night rendezvous and saving the world from nuclear destruction. Thanks so much for being with us, Professor.

CARTER: It is really my pleasure as always.

SIMON: The story opens - your protagonist, Margo Jensen, brilliant 19-year-old Cornell student from family of means that happens to be African-American, enlisted in a covert operation to accompany Bobby Fischer.

CARTER: You know, it's interesting. When I talk to people about this story, a lot of people are immediately skeptical. They say, come on, how could a 19-year-old even have an affair with the president?

CARTER: (Laughing) Well, you know, we know now that while he was in the White House, President Kennedy really did have an affair with a 19-year-old intern. We also know that during the Cuban missile crisis, in addition to the official negotiations, there were secret negotiations hidden even from most of Kennedy's closest advisers, known as the back channel. My fictional premise, as it were, is supposed that the affair with the 19-year-old intern is a cover for the back channel negotiations. So if anybody finds out about it, they'll think the president's having an affair, not that he's doing secret negotiations. And that's how Margo, my protagonist, gets drawn into the story. She's the only person that will do. She has to go to Washington to serve as this negotiator. There are a lot of different reasons that only she will do and those reasons, as I say, unfold throughout the narrative.

SIMON: Every time I've interviewed somebody from the period of the Cuban missile crisis, they have said, you have no idea how close we came to blowing up the world. I wonder, having immersed yourself in that period with this novel, how you feel about that.

CARTER: The Cuban missile crisis is as close as the world ever came to nuclear annihilation. And it's easy nowadays to forget that or to just let it kind of flow it's piece of distant history. But you had submarines ready to fire on ships and destroyers ready to fire on submarines. You had U.S. forces massed in South Florida ready to invade Cuba. There was this moment when the cities were being evacuated all up and down the East Coast and in other places as well. We really were on the brink of a war that would likely have ended civilization. And in that moment, President Kennedy had a lot of vitally important decisions and very difficult decisions to make. And history shows he made them rather well.

SIMON: You've got a line at one point - President Kennedy complains that the CIA can count missile launchers on the ground in Cuba but they don't know what's going on in the highest councils of Moscow. It's a good week to ask if that's going on today.

CARTER: It's a continuing problem. That is - things that can be picked up technologically - we can do extremely well. Things that involve developing human sources on the ground - the truth is we're getting worse and worse. We're not just doing it as well as we used to, and it was already a problem back then.

A lot of the papers - a lot of the transcripts and so on are now available of the internal deliberations of the Kennedy administration. A constant problem was the inability of American intelligence to predict Russian actions as recently as the summer when the missiles were already being put in Cuba, but the U.S. didn't know they were there yet. The CIA was reporting to the White House that there was very little chance that the Russians would ever take the risk of putting missiles in Cuba. And they just didn't really have a clue what was going on.

SIMON: And as we take a look at the relations today between the United States and Russia, you hear a lot of voices saying we don't want another Cold War. I closed your book and wondered, well, we don't want to skate close to nuclear annihilation again. I wonder if there wasn't a kind of - I don't know - constancy, predictability in the Cold War.

CARTER: Foreign-policy is very hard, and it's very difficult, I think, to sit in a studio and decide what the president should really be doing. But I will say this. There's one thing that Kennedy did extremely well. He kept his adversary guessing. To this day, you cannot glean from the records whether Kennedy was willing to push the button or not. We just don't know. The point is Khruschev became so persuaded that he might press the button, that he backed down. And it's keeping your adversary guessing very often that is the key, in conflict negotiation, to being on the winning rather than losing side.

SIMON: Stephen Carter. His new novel - "Back Channel." Thanks so much for being with us.